Improved nursery rearing method for Asian seabass fingerlings as an additional income generation activity.

Abstract

Farming of commercially important brackishwater and marine finfish is steadily growing due to the increasing demand for high value fish in domestic and export markets. Increased awareness among the consumers about proven health benefits on consuming marine finfish also lead to higher level consumption and demand. Hence, marine finfish culture in open seas, backwaters and lagoons is one of the fastest growing sub-sectors of aquaculture in the world. India is bestowed with a vast coastline of 8,118 km with an Exclusive Economic Zone (EEZ) of 2.02 million km2 . The marine capture fishery is dominated by the socio economically backward small-scale fishers living near the seashore. Stocks of high valued marine finfish are declining due to over-exploitation or environmental degradation. Hence, to increase the fish production and to support the livelihood of the fishermen living in the coastal areas, marine and brackishwater fish farming is taken up as an important activity. Breeding and seed production technologies for various commercially important finfish have been standardized by the ICAR institutes including CIBA and CMFRI. The most common cultivable candidate species of marine finfishes includes the Asian seabass (Lates calcarifer), milkfish (Chanos chanos), grey mullet (Mugil cephalus), groupers (Epinephelus spp.), cobia (Rachycentron canadum), carangids; silver pompano (Trachinotus blochii) and Indian pompano (T. mookalee), snappers (Lutjanus spp.), rabbit fish (Siganus spp.) and sea breams (Lethrinus spp., Sparus spp.). Commercial scale seed production of many high value marine finfishes is technology oriented and expensive due to the high costs involved in the establishment of hatchery facilities. Further, it also involves complicated larval rearing process involving culture of high-quality live feeds, their nutritional enrichment, feeding protocols, grading, water quality management, nursery rearing and health management. Similarly, nursery rearing is another phase in the seed rearing process, through which stockable size fingerlings for cage or pond culture are produced which increases the survival rate in the grow-out phase and reduces the culture period. Commercially important Asian seabass culture is one of the most practiced and profitable sector of fish farming in the brackish and marine waters. It has good flesh texture, taste, high market value and demand. Due to euryhaline nature, seabass can be reared both in freshwater and saltwater conditions.Asian seabass grows rapidly up to 1.2 to 1.5 kg size within a culture period of 12 months in freshwater and brackishwater environments. It is a carnivorous fish and highly cannibalistic in nature and attack the smaller size fishes leading to low survival rate in the farming